1. Field of the Invention
The present invention relates to a solar cell that converts light energy into electrical energy and a solar cell color adjusting method of adjusting the external color of the solar cell.
2. Description of the Related Art
In recent years, real spread of photovoltaic power generation is expected from the viewpoint of global environmental conservation, so that solar cells are actively developed. The solar cell is a battery device that converts light energy of sunlight into electrical energy (so-called photoelectric conversion).
The solar cell has a stacking structure obtained by stacking mainly, on a substrate, a reflecting electrode layer, a photoelectric conversion layer (so-called power generation layer), and a transparent electrode layer in this order. In a solar cell of this kind, incident light (sunlight) led to the inside the solar cell via the transparent electrode layer is reflected by the reflecting electrode layer. When the reflection light is led to the outside of the solar cell via the transparent electrode layer again, power is generated in the photoelectric conversion layer.
With respect to the configuration of the solar cell, some modes have been already proposed. Concretely, a technique is known in which when the photoelectric conversion layer is made of amorphous silicon, by constructing the reflecting electrode layer so as to have a stacking structure in which a layer of metal or alloy (first metal layer), and a layer of metal, alloy, stainless steel, or silicon steel alloy (second metal layer) are stacked in order, adhesion between the photoelectric conversion layer and the reflecting electrode layer is enhanced and mutual diffusion between them is prevented (refer to, for example, Japanese Patent Publication No. Hei 02-006235).
In recent years, a solar cell for low-illumination-level use mounted on, for example, a watch or the like is in increase demand not only from the viewpoint of battery properties such as power generation performance but also from the viewpoint of design-conscious external appearance. Concretely, in a solar cell whose photoelectric conversion layer is made of amorphous silicon, external color takes on redness due to the light absorbing property of amorphous silicon. To make the solar cell inconspicuous in the external appearance of the watch, it is necessary to adjust the external color so that the redness is suppressed.
However, a conventional solar cell has a problem such that, since concrete countermeasures are not taken from the viewpoint of adjusting the external color, it is difficult to adjust the external color in accordance with a demand for color tones.